Separate layer fracturing sand control packer, construction pipe column and method

Abstract

The invention discloses a separate layer fracturing sand control packer, a construction pipe column and a method, and belongs to the technical field of oil and gas exploitation. An upper composite slip, an upper cone, a composite rubber barrel, a lower cone and a lower composite slip are sequentially arranged on the periphery of a central pipe from top to bottom, the bottom of a connecting sleeve is connected with the bottom of the central pipe, a hydraulic cylinder used for driving a piston is arranged between the upper middle portion of the connecting sleeve and the central pipe, the hydraulic cylinder is communicated with the central pipe, and the piston is located below the lower composite slip. And a shear pin is connected between the piston and the central pipe. The dissolvable packer has the beneficial effects that the dissolvable packer adopts the composite rubber sleeve and the composite slip, after fracturing construction, the composite rubber sleeve and the composite slip can be dissolved by squeezing and injecting acid liquid, so that the dissolvable packer is automatically unsealed, and the dissolvable packer is very beneficial to later well repair and pipe column salvage.

Description

Technical Field

[0001] The invention relates to a layered fracturing sand control packer, a construction pipe string and a method, and belongs to the technical field of oil and gas extraction. Background Art

[0002] Fracturing sand control technology involves hydraulically fracturing to open up the formation, then filling the fractures and depletion zones with resin sand at varying sand ratios. This process, through end-of-line sand removal, creates wide, short fractures that penetrate the contaminated zone near the wellbore, altering the near-wellbore seepage pattern and pressure distribution around the wellbore. This technology also forms a high-strength, high-permeability artificial wellbore sand barrier, achieving the dual effects of "sand control and production increase." This technology boasts excellent sand control effectiveness, a wide range of applications, and the ability to eliminate the need for a tubing string in the wellbore after sand control, making it widely used in oilfields.

[0003] However, according to field practice, the effectiveness of fracturing and sand control measures for heterogeneous multi-oil layers in long well sections is relatively short. The main reason for this is that the resin sand is unevenly filled in the multiple oil layers, and the amount of resin sand filled in some layers is small, resulting in the failure to form a complete sand barrier. This problem can be effectively solved by adopting a segmented sand control process to fill the resin sand layer by layer. However, the current mechanical layered fracturing and sand control process mainly uses a combination of multiple packers and sliding sleeves to achieve layered filling construction. Due to the large number of downhole packers and the complex structure of the tubing, it cannot be unsealed after being set. Resin sand falling into the annulus can easily cause sand jamming and sand burial, making it difficult to salvage the construction tubing, resulting in major repair operations. Due to the existence of this risk, the layered fracturing and sand control process is currently difficult to promote and apply on site. Summary of the Invention

[0004] In order to solve the defects of the prior art, the purpose of the present invention is to provide a layered fracturing sand control packer, a construction string and a method to improve the adaptability, pertinence and safety of the layered fracturing sand control process.

[0005] The technical solution of the present invention is: a soluble sealer, the outer circumference of the central tube is provided with an upper composite slip, an upper cone, a composite rubber cylinder, a lower cone and a lower composite slip in sequence from top to bottom, the bottom of the connecting sleeve is connected to the bottom of the central tube, and a liquid cylinder for driving the piston is provided between the upper middle part of the connecting sleeve and the central tube, the liquid cylinder is connected to the central tube, the piston is located below the lower composite slip, and a shear pin is connected between the piston and the central tube.

[0006] The upper composite slip and the lower composite slip are both provided with hard tooth claws which are not acid decomposed.

[0007] The hard tooth claws are made of hard alloy or ceramic material.

[0008] The composite rubber cylinder comprises a soluble rubber cylinder and an outer protective layer coated on the outer surface of the soluble rubber cylinder.

[0009] The soluble rubber tube is made of acid-decomposable magnesium-aluminum alloy.

[0010] The present invention also claims protection for a layered fracturing sand control string with soluble packers, wherein a plurality of soluble packers are provided on the oil pipe, a fracturing sliding sleeve is connected below the soluble packers, and a casing shoe is connected to the bottom of the oil pipe.

[0011] A perforated pipe is connected below the fracturing sliding sleeve, and a hole plug is provided at the hole of the perforated pipe. The hole plug is a frustum-shaped soluble hole plug.

[0012] The frustum-shaped soluble hole plug and the seating ball seat of the fracturing sleeve are both made of acid-decomposable magnesium-aluminum alloy. The inner diameters of the seating ball seats decrease step by step from top to bottom along the oil pipe, with a step difference of 5 mm.

[0013] The present invention also seeks to protect a construction method for a layered fracturing sand control pipe string, comprising the following steps:

[0014] Step 1: Run the assembled soluble packer layered fracturing completion string into the wellbore, adjust the string depth, place the casing shoe at the lower boundary of the fracturing layer, the top packer at the upper boundary of the fracturing layer, and distribute the fracturing sleeve and soluble perforated pipe to each fracturing layer;

[0015] Step 2: Reversely replace the fracturing fluid from the oil casing annulus to clean the wellbore and prevent impurities from fracturing the formation;

[0016] Step 3: Place the soluble fracturing ball matched with the fracturing sleeve in the primary fracturing layer, pressurize the surface to 20-30 MPa, and set the soluble packer in the primary fracturing layer;

[0017] Step 4: Continue to pressurize to 25MPa, open the fracturing sleeve at the primary fracturing layer, perform fracturing construction on the primary fracturing layer, and squeeze in acid curing agent at the end of sand filling;

[0018] Step 5: Put the soluble fracturing ball matched with the fracturing sleeve into the secondary fracturing layer, pressurize the ground to 25MPa, open the fracturing sleeve at the secondary fracturing layer, and perform fracturing construction on the secondary fracturing layer. At the end of sand filling, squeeze in the acid curing agent;

[0019] Step 6: Similarly, fracturing construction is carried out on each level of fracturing layer on the upper part, and the fracturing layers are increased step by step from bottom to top;

[0020] Step 7: Shut in the well for 24-72 hours to allow the resin sand to solidify and the acid to dissolve the soluble packer;

[0021] Step 8: Pull out the construction pipe string and put the pump into production.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The soluble packer uses a composite rubber tube and a composite slip. After fracturing construction, the composite rubber tube and the composite slip can be dissolved by squeezing acid, so that the soluble packer is automatically unsealed, which is very beneficial for the later well repair and salvage of the tubing.

[0024] (2) The composite rubber sleeve adopts a protective layer to prevent the soluble rubber sleeve from dissolving and being damaged prematurely; the soluble body strength of the composite slip is relatively low. By installing hard claws, the bite force between the slip and the casing is improved, which plays a good anchoring role for the packer.

[0025] (3) The soluble hole plug of the soluble perforated pipe adopts a cone-shaped structure, which is sealed by the pressure inside the pipe. The more it is pressed, the tighter it is, which improves the internal pressure resistance of the soluble perforated pipe and meets the requirements of fracturing construction.

[0026] (4) After acid dissolution, the hole plug of the soluble perforated pipe increases the production channel, which is conducive to the return of proppant and formation sand outside the pipe string, avoiding their accumulation outside the pipe and causing sand jam.

[0027] (5) The casing shoe of the completion string is located at the bottom of the fracturing layer. During the slurry replacement stage, the fracturing sleeve is in a closed state and the perforated pipe holes are in a temporarily blocked state, which ensures that all the mud in the wellbore is replaced and reduces reservoir pollution and oil pipe blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the structure of a soluble packer;

[0029] Figure 2 for Figure 1 A partial enlarged view of

[0030] Figure 3 Schematic diagram of the structure of the sand control string for layered fracturing Figure 1 ;

[0031] Figure 4 Schematic diagram of the structure of the sand control string for layered fracturing Figure 2 .

[0032] The reference numerals in the figure are as follows: 1. central pipe, 2. upper composite slip, 3. upper cone, 4. composite rubber cylinder, 5. lower cone, 6. lower composite slip, 7. shear pin, 8. hydraulic cylinder, 9. connecting sleeve, 10. oil pipe, 11. soluble packer, 12. fracturing sleeve, 13. casing shoe, 14. perforated pipe, 15. wellbore, 16. primary fracturing layer, 17. secondary fracturing layer. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] Next, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views of device structures may be partially enlarged and not to scale when describing the embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0037] The following is combined with Figure 1-4 The present invention is further described in detail: This application is further described using this example.

[0038] The present invention controls the external heating temperature by controlling the internal temperature of the catalytic material bed. When the internal temperature of the bed reaches the decomposition temperature, the external heating is kept at a constant temperature and an inert gas is introduced to discharge the heat in time to ensure that the bed reaction temperature does not exceed the upper limit.

[0039] When the metal salt or organic compound reaches the decomposition temperature, the vacuum system is turned on to fully discharge the gas inside the pores of the catalytic material to ensure that the metal salt or organic compound in the catalytic material is fully decomposed.

[0040] Example 1

[0041] A soluble packer is provided. The outer periphery of a central pipe 1 is provided with, from top to bottom, an upper composite slip 2, an upper cone 3, a composite rubber sleeve 4, a lower cone 5, and a lower composite slip 6. The bottom of a connecting sleeve 9 is connected to the bottom of the central pipe 1. A hydraulic cylinder 8 for driving a piston is provided between the upper middle portion of the connecting sleeve 9 and the central pipe 1. The hydraulic cylinder 8 is in communication with the central pipe 1. The piston is located below the lower composite slip 6. A shear pin 7 is connected between the piston and the central pipe 1. Both the upper composite slip 2 and the lower composite slip 6 are provided with hard teeth that are not acid-disintegrated. The hard teeth are made of cemented carbide or ceramic. The composite rubber sleeve 4 includes a soluble rubber sleeve and an outer protective layer coated on the outer surface of the soluble rubber sleeve. The soluble rubber sleeve is made of an acid-disintegratable magnesium-aluminum alloy. The soluble rubber sleeve is soluble in acid. The outer protective layer is insoluble in drilling and completion fluids. When the soluble rubber sleeve deforms and expands, the outer protective layer is damaged and falls off.

[0042] Before working, the soluble packer is lowered into the wellbore 15, and then hydraulic pressure is injected into the oil pipe 10. Under the action of hydraulic pressure, the piston pushes the lower composite slip 6 upward, and the lower composite slip 6 pushes the lower vertebra 5 upward. The lower vertebra 5 pushes the composite rubber cylinder 4, and the composite rubber cylinder 4 pushes the upper vertebra 3 upward. The upper vertebra 3 moves to the upper composite slip 2. The top of the upper composite slip 2 cannot move upward due to the limit. The cone surface of the upper vertebra 3 is inserted into the upper composite slip 2, and the upper composite slip 2 is expanded and hardened. The hard claws are stuck on the inner wall of the wellbore 15, and the upper vertebral body 3 stops moving after moving to the limit position. The lower vertebral body 5 continues to move upward, squeezing and expanding the composite rubber tube 4. The outer protective layer of the composite rubber tube 4 cracks and falls off, and the soluble rubber tube expands and squeezes the outer inner wall of the wellbore 15. When the lower vertebral body 5 can no longer move upward, the lower composite slip 6 continues to move upward, and the lower composite slip 6 moves along the conical surface of the lower vertebral body 5. The lower composite slip 6 is expanded, and the hard claws are stuck on the inner wall of the wellbore 15.

[0043] Example 2

[0044] A layered fracturing sand control string with soluble packers is provided on an oil pipe 10. A plurality of soluble packers 11 are provided on the oil pipe 10. A fracturing sliding sleeve 12 is connected below the soluble packers 11. A casing shoe 13 is connected to the bottom of the oil pipe 10.

[0045] The fracturing sleeve 12 is connected to a perforated pipe 14 below. The perforated pipe 14 is provided with a plug at the hole of the perforated pipe 14. The plug is installed in the hole of the perforated pipe 14 by threading or welding. The plug is a frustum-shaped soluble plug. The bottom surface of the frustum is larger than the top surface. The bottom surface of the soluble plug is located on the inside of the perforated pipe 14, and the top surface of the soluble plug is located on the outside of the perforated pipe 14. The frustum-shaped structure can achieve a better sealing effect during pressure. The frustum-shaped soluble plug and the sealing ball seat of the fracturing sleeve 12 are both made of acid-degradable magnesium-aluminum alloy. After the soluble plug is acid-degraded, the holes of the perforated pipe 14 are conducive to the return of proppant and formation sand outside the pipe string, avoiding their accumulation outside the pipe and causing sand jams. The inner diameter of several sealing ball seats decreases step by step from top to bottom along the oil pipe 10, with a step difference of 5mm.

[0046] Example 3

[0047] The construction method of the layered fracturing sand control pipe string includes the following steps:

[0048] Step 1: Lower the assembled soluble packer 11 layered fracturing completion string into the wellbore 15, adjust the string depth, place the casing shoe 13 at the lower boundary of the fracturing layer, place the top packer at the upper boundary of the fracturing layer, and distribute the fracturing sleeve and soluble perforated pipe to correspond to each fracturing layer section;

[0049] Step 2: Reversely replace the fracturing fluid from the oil casing annulus to clean the wellbore and prevent impurities from fracturing the formation;

[0050] Step 3: Put the soluble fracturing ball matched with the fracturing sleeve 12 into the primary fracturing layer 16, pressurize the surface to 20-30 MPa, and set the soluble packer 11 at the primary fracturing layer 16;

[0051] Step 4: Continue to pressurize to 25 MPa, open the fracturing sleeve 12 at the primary fracturing layer 16, perform fracturing construction on the primary fracturing layer 16, and squeeze in acid curing agent in the later stage of sand filling;

[0052] Step 5: Put the soluble fracturing ball matched with the fracturing sleeve 12 into the secondary fracturing layer 17, pressurize the ground to 25MPa, open the fracturing sleeve 12 at the secondary fracturing layer 17, and perform fracturing construction on the secondary fracturing layer 17. At the end of sand filling, squeeze in the acid curing agent;

[0053] Step 6: Similarly, fracturing construction is carried out on each level of fracturing layer on the upper part, and the fracturing layers are increased step by step from bottom to top;

[0054] Step 7: Shut in the well for 24-72 hours to allow the resin sand to solidify while the acid solution dissolves the soluble packer 11;

[0055] Step 8: Pull out the construction pipe string and put the pump into production.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A soluble packer, characterized in that: The outer periphery of the central tube (1) is provided with an upper composite slip (2), an upper vertebral body (3), a composite rubber cylinder (4), a lower vertebral body (5) and a lower composite slip (6) in sequence from top to bottom. The bottom of the connecting sleeve (9) is connected to the bottom of the central tube (1). A liquid cylinder (8) for driving a piston is provided between the upper middle portion of the connecting sleeve (9) and the central tube (1). The liquid cylinder (8) is communicated with the central tube (1). The piston is located below the lower composite slip (6). A shear pin (7) is connected between the piston and the central tube (1).

2. The soluble packer according to claim 1, characterized in that: The upper composite slip (2) and the lower composite slip (6) are both provided with hard teeth claws that are not acid-decomposed.

3. The soluble packer according to claim 2, characterized in that: The hard tooth claws are made of hard alloy or ceramic material.

4. The soluble packer according to claim 1, characterized in that The composite rubber cylinder (4) comprises a soluble rubber cylinder and an outer protective layer coated on the outer surface of the soluble rubber cylinder.

5. The soluble packer according to claim 4, characterized in that: The soluble rubber tube is made of acid-decomposable magnesium-aluminum alloy.

6. A layered fracturing sand control string comprising the soluble packer according to any one of claims 1 to 5, characterized in that: A plurality of soluble packers (11) are provided on the oil pipe (10), a fracturing sliding sleeve (12) is connected below the soluble packers (11), and a casing shoe (13) is connected to the bottom of the oil pipe (10).

7. The layered fracturing sand control string according to claim 6, characterized in that: The fracturing sleeve (12) is connected to a perforated pipe (14) below, and a hole plug is provided at the hole of the perforated pipe (14), and the hole plug is a frustum-shaped soluble hole plug.

8. The layered fracturing sand control string according to claim 7, characterized in that: The materials of the cone-shaped soluble hole plug and the sealing ball seat of the fracturing sleeve (12) are both acid-decomposable magnesium-aluminum alloy, and the inner diameters of the sealing ball seats decrease step by step from top to bottom along the oil pipe (10), with a step difference of 5 mm.

9. The construction method of the layered fracturing sand control string according to claim 7, characterized in that: The steps include: Step 1: lowering the assembled soluble packer (11) layered fracturing completion string into the wellbore (15), adjusting the string depth, positioning the casing shoe (13) at the lower boundary of the fracturing layer, the top packer at the upper boundary of the fracturing layer, and distributing the fracturing sleeve and the soluble perforated pipe to correspond to each fracturing layer section; Step 2: Reversely replace the fracturing fluid from the oil casing annulus to clean the wellbore and prevent impurities from fracturing the formation; Step 3: Putting a soluble fracturing ball matched with the fracturing sleeve (12) into the primary fracturing layer (16), applying ground pressure of 20-30 MPa, and setting the soluble packer (11) at the primary fracturing layer (16); Step 4: Continue to pressurize to 25 MPa, open the fracturing sleeve 11 at the primary fracturing layer (16), perform fracturing construction on the primary fracturing layer (16), and squeeze in acid curing agent in the later stage of sand filling; Step 5: Put the soluble fracturing ball matched with the fracturing sleeve (12) into the secondary fracturing layer (17), pressurize the ground to 25MPa, open the fracturing sleeve (12) at the secondary fracturing layer (17), perform fracturing construction on the secondary fracturing layer (17), and squeeze in the acid curing agent in the later stage of sand filling; Step 6: Similarly, fracturing construction is carried out on each level of fracturing layer above, and the number of fracturing layers increases step by step from bottom to top; Step 7: shut in the well for 24-72 hours to allow the resin sand to solidify while the acid solution dissolves the soluble packer (11); Step 8: Pull out the construction pipe string and put the pump into production.

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